The Kremlin dismissed allegations that Russia had run a sophisticated doping program at the last winter Olympics as treacherous slander on Friday, calling the ex-head of the country’s doping laboratory “a turncoat.”

The new allegations pile pressure on Sports Minister Vitaly Mutko, and are likely to make it harder for Moscow to overturn the Rio athletics ban.

“These allegations look absolutely groundless,” Dmitry Peskov, a Kremlin spokesman, told reporters in a conference call on Friday. “They are not substantiated by any trustworthy data, they are not backed by any sort of documents. All this simply looks like slander by a turncoat.”

The Kremlin had not changed its view of Mutko in light of the new accusations, Peskov said when asked. Mutko, who has been in his position since 2008, has called the allegations “nonsense.”

Asked about the prospects of Russian track and field athletes being allowed to compete in Rio, Peskov said: “We hope everything will be fine.”

Two of the sportsmen named in the New York Times report, cross-country skier Alexander Legkov and bobsledder Alexander Zubkov, on Friday rejected the allegations against them as “nonsense and slanderous.”

“We need to take legal action against these people,” Legkov told Russia’s Match TV. “All of it (the allegations) is frivolous, it is complete garbage and we need to stop it.

It’s the second major scandal to hit the International Olympic Committee this week, after revelations of irregular payments by representatives of Tokyo’s successful bid to host the summer 2020 games. French prosecutors confirmed earlier this week that the Tokyo bid committee had transferred at least $1.5 million to a secret account linked to the son of Lamine Diack, the disgraced former world track and field president.